环境因素对单增李斯特菌inlB毒力基因表达的影响

针对单增李斯特菌毒力基因inl B设计五对引物,从中筛选出一对特异性强的引物,利用反转录荧光定量PCR技术来考察毒力基因表达的强弱。在不同环境因素条件下培养单增李斯特菌,分别提取菌体RNA,继而合成c DNA,以管家基因16S r RNA为内参基因,利用循环阈值(Ct)的变化计算inl B基因的相对表达量。结果表明,毒力基因inl B在温度为15℃、p H为6、氯化钠浓度为1.5%~2.0%、蔗糖浓度为0.75%~1.25%时能高效表达;温度为0℃和45℃、p H为4和9、氯化钠浓度为3.5%以上以及蔗糖浓度为0%~0.25%和2.25%以上时,对毒力基因inl B的表达起明显的抑制作用;在p H为6的条件下,酸的种类对毒力基因inl B的表达影响不大。      

植物乳杆菌ST-ⅢproU基因簇的克隆、表达

分离自泡菜的植物乳杆菌ST-Ⅲ能够在盐浓度高达8%的环境下存活,其特有的质粒上存在一个与转运相容性溶质相关的proU基因簇,系统发育分析发现,proU基因簇与耐盐能力较高的戊糖乳杆菌IG1相应基因的相似性达100%,因此推测proU可能与植物乳杆菌ST-Ⅲ的耐盐能力相关。将proU及其包含的基因proX、proW、proV分别克隆到质粒pNZ8148上,并电转化到耐盐能力较低的乳酸乳球菌NZ9000中。重组菌株在添加3%NaCl和1mmol/L甜菜碱的化学成分确定培养基（CDM）中培养,以原始菌株乳酸乳球菌NZ9000（pNZ8148）为对照,测定耐盐能力。结果表明,各个基因均能在重组菌中表达,表达量与对照菌株相比至少提高了106倍,且重组菌株的耐盐能力均优于对照菌株,因此,proU与植物乳杆菌ST-Ⅲ耐盐能力直接相关。      

Pivotal Role of Phytohormones and Their Responsive Genes in Plant Growth and Their Signaling and Transduction Pathway under Salt Stress in Cotton

The presence of phyto-hormones in plants at relatively low concentrations plays an indispensable role in regulating crop growth and yield. Salt stress is one of the major abiotic stresses limiting cotton production. It has been reported that exogenous phyto-hormones are involved in various plant defense systems against salt stress. Recently, different studies revealed the pivotal performance of hormones in regulating cotton growth and yield. However, a comprehensive understanding of these exogenous hormones, which regulate cotton growth and yield under salt stress, is lacking. In this review, we focused on new advances in elucidating the roles of exogenous hormones (gibberellin (GA) and salicylic acid (SA)) and their signaling and transduction pathways and the cross-talk between GA and SA in regulating crop growth and development under salt stress. In this review, we not only focused on the role of phyto-hormones but also identified the roles of GA and SA responsive genes to salt stress. Our aim is to provide a comprehensive review of the performance of GA and SA and their responsive genes under salt stress, assisting in the further elucidation of the mechanism that plant hormones use to regulate growth and yield under salt stress.     

Dipotassium Glycyrrhizinate on Melanoma Cell Line: Inhibition of Cerebral Metastases Formation by Targeting NF-kB Genes-Mediating MicroRNA-4443 and MicroRNA-3620—Dipotassium Glycyrrhizinate Effect on Melanoma

Glycyrrhizic acid (GA), a natural compound isolated from licorice (Glycyrrhiza glabra), has exhibited anti-inflammatory and anti-tumor effects in vitro. Dipotassium glycyrrhizinate (DPG), a dipotassium salt of GA, also has shown an anti-tumor effect on glioblastoma cell lines, U87MG and T98G. The study investigated the DPG effects in the melanoma cell line (SK-MEL-28). MTT assay demonstrated that the viability of the cells was significantly decreased in a time- and dose-dependent manner after DPG (IC₅₀ = 36 mM; 24 h). DNA fragmentation suggested that DPG (IC₅₀) induced cellular apoptosis, which was confirmed by a significant number of TUNEL-positive cells (p-value = 0.048) and by PARP-1 [0.55 vs. 1.02 arbitrary units (AUs), p-value = 0.001], BAX (1.91 vs. 1.05 AUs, p-value = 0.09), and BCL-2 (0.51 vs. 1.07 AUs, p-value = 0.0018) mRNA compared to control cells. The proliferation and wound-healing assays showed an anti-proliferative effect on DPG-IC₅₀-treated cells, also indicating an inhibitory effect on cell migration (p-values < 0.001). Moreover, it was observed that DPG promoted a 100% reduction in melanospheres formation (p-value = 0.008). Our previous microRNAs (miRs) global analysis has revealed that DPG might increase miR-4443 and miR-3620 expression levels. Thus, qPCR showed that after DPG treatment, SK-MEL-28 cells presented significantly high miR-4443 (1.77 vs. 1.04 AUs, p-value = 0.02) and miR-3620 (2.30 vs. 1.00 AUs, p-value = 0.01) expression compared to control cells, which are predicted to target the NF-kB, CD209 and TNC genes, respectively. Both genes are responsible for cell attachment and migration, and qPCR revealed significantly decreased CD209 (1.01 vs. 0.54 AUs, p-value = 0.018) and TNC (1.00 vs. 0.31 AUs, p-value = 2.38 × 10⁻⁶) mRNA expression levels after DPG compared to untreated cells. Furthermore, the migration of SK-MEL-28 cells stimulated by 12-O-tetradecanoylphorbol-13-acetate (TPA) was attenuated by adding DPG by wound-healing assay (48 h: p-value = 0.004; 72 h: p-value = 7.0 × 10⁻⁴). In addition, the MMP-9 expression level was inhibited by DPG in melanoma cells stimulated by TPA and compared to TPA-treated cells (3.56 vs. 0.99 AUs, p-value = 0.0016) after 24 h of treatment. Our results suggested that DPG has an apoptotic, anti-proliferative, and anti-migratory effect on SK-MEL-28 cells. DPG was also able to inhibit cancer stem-like cells that may cause cerebral tumor formation.     

2009-2018年广州市即食食品中金黄色葡萄球菌污染情况和菌型特征

目的 分析2009-2018年广州市零售即食食品中金黄色葡萄球菌污染情况,以及菌株肠毒素基因、耐药表型特征.方法 从广州市辖11个区的农贸市场、超市随机购买零售即食食品,增菌后分离金黄色葡萄球菌.对所有菌株进行多位点序列分型(MLST)、抗生素敏感性试验,并检测24种肠毒素基因.对耐甲氧西林金黄色葡萄球菌(MRSA)进...     

2016—2017年广西食用植物油质量安全监测评价分析

对广西食用植物油质量安全水平和污染程度进行监测评价。2016—2017年对广西14个地级市共抽检监测食用植物油3 821份,按照 GB/T 5009 检测酸价、过氧化值、浸出油溶剂残留、黄曲霉毒素B1、总砷、铅和苯并(a)芘,并依据 GB 2716—2005对食用油进行评价。结果表明：抽检食用植物油总合格率为 92.04%;2016、2017年食用植物油合格率分别为96.70%和91.22%,差异有统计学意义（P<0.05）。从种类看,玉米油、芝麻油和其他食用植物油合格率分别为100%、93.75%和99.61%。花生油合格率最低,为87.83%,黄曲霉毒素B1超标是花生油不合格的主要原因,检出率为8.85%。从包装看,预包装食用植物油的合格率（99.70%）明显高于散装（83.72%）,差异有统计学意义（P<0.05）。食用植物油生产加工环节的合格率最低,为88.01%。广西玉米油、芝麻油和其他食用植物油相对而言抽检合格率较高,花生油合格率较低,应加强花生油的抽检监测和监督管理,通过严格落实生产经营者主体责任,积极引导消费者科学理性消费,持续深化小油坊专项治理,不断强化质量安全控制技术研究,逐步推进广西食用植物油安全水平稳步提升。     

烟台地区食源性疾病中副溶血性弧菌的病原特征及溯源分析

目的了解烟台地区引发食物中毒的副溶血性弧菌分离菌株的主要血清型、抗生素耐药情况、致病力的强弱以及传播流行趋势。方法对2017～2019年11起食物中毒爆发事件中分离的14株副溶血性弧菌进行血清分型;采用微量肉汤稀释法进行药敏试验;采用PCR技术检测毒力基因不耐热溶血素(tld)、耐药直接溶血素(tdh)和溶血相关溶血素(trh);采用脉冲场电泳(pulse-field gel electrophoresis,PFGE)进行分子分型的溯源分析。结果引发烟台地区食物中毒爆发的副溶血性弧菌血清型多样,但以O3:K6型为主(28.6%),分离菌株中11株(78.6%)表现为tdh阳性和trh阴性,3株(21.4%)未携带tdh和trh基因,对头孢唑啉(71.4%)、多粘菌素E(57.1%)、美罗培南和阿莫西林/克拉维酸(7.1%)均出现耐药情况,对氨苄西林(21.4%)、多粘菌素B(14.3%)为中度敏感,耐药谱显示没有出现对3种以上同时耐药的情况,但是42.9%的分离菌株对2种同时耐药情况。结论烟台地区引发食物中毒爆发的副溶血性弧菌以O3:K6型为主,主要携带tdh,对头孢唑啉耐药和多粘菌素耐药普遍存在,具有聚集性爆发的风险,因此加强腹泻病的监测,充分利用国家致病菌识别网集中进行本地区分离菌株的病原特征研究是防控食物中毒爆发的有效手段。     

Antimicrobial resistant genes associated with Salmonella from retail meats and street foods

We examined the antimicrobial resistance of Salmonella isolates from 300 meat products (raw beef, chicken meat and street foods). A total of 88 non-duplicate Salmonella from 66 (22.0%) retail meat and 22 (7.5%) street food samples were recovered and 11 serovars were identified. Among the 88 Salmonella isolates, the highest resistance was to tetracycline (73.8%), followed by sulfonamide (63.6%), streptomycin (57.9%), nalidixic acid (44.3%), trimethoprim–sulfamethoxazole (19.3%), ampicillin (17.0%), chloramphenicol (10.2%), cephalotin (8.0%), kanamycin (6.8%), ciprofloxacin (2.2%) gentamycin (2.2%), cefoxitin (2.2%), amoxicillin–clavulanate (1.0%) and amikacin (1.0%). Sixty-seven percent of the isolates (59/88) were multidrug resistant (MDR). Ten out of 17 resistance genes (bla_TEM-1, strA, strB, aadA, sulI, sulII, tetA, tetB, floR, cmlA) were detected. Twelve of the 59 MDR Salmonella isolates from serovars Typhimurium (6), Newport (3), Agona (1), Albany (1) and Weltevreden (1) had class 1 integrons. The gene cassettes identified were dfrA1, dfrV, dfrA12, aadA2, sul1 genes and an open reading frame orfC of unknown function. Four integron-positive isolates could transfer resistance phenotypes to the recipient strain, E. coli J53 via conjugation. These data revealed that the Salmonella isolates recovered from the retail meats and cooked street foods were resistant to multiple antimicrobials, which can be transmitted to humans through food products. The occurrence of mobile genetic elements such as integrons reiterates the roles of food of animal origins as a reservoir of MDR Salmonella.     

云南省部分食品黄曲霉毒素B1膳食暴露风险评估

目的评估云南省部分食品中黄曲霉毒素B1(aflatoxinB1,AFB1)膳食暴露风险。方法结合2012～2017年云南省部分地区市售大米及其制品、玉米及其制品等6类主要食品的黄曲霉毒素B1含量数据,以及本省营养监测消费量数据,采用点评估方法对云南省居民AFB1暴露水平进行评估。结果云南省全人群来源于6类食品的AFB1暴露量为1.02×10-3μg/kgbw,其中来源于大米的AFB1暴露量最高,占总暴露量的50.98%,其次是玉米及其制品,占18.63%。总暴露量为大城市贫困农村中小城市一般农村;云南省居民AFB1膳食暴露量对肝癌发病率的贡献为0.040/10万人;各地区居民暴露边界比(margin of exposure, MOE)值介于144.07～180.85之间。结论云南省AFB1污染状况相对良好,仍需持续关注; 6类食物中大米、玉米是云南省AFB1的主要暴露来源。